I. Field of the Invention
The present invention relates generally to grain harvesting machines, and more particularly, to improved row units for harvesting combines to thereby reduce yield loss during harvesting.
II. Discussion of the Prior Art
A cornhead for a harvesting combine generally comprises a plurality of side-by-side row units that are laterally spaced from one another so as to engage adjacent rows of growing corn plants as the combine is being driven through a standing field of corn. Each row unit comprises a pair of horizontal stripper plates mounted on a frame so that a gap of a predetermined width, slightly greater than the diameter of the cornstalks to be harvested, is provided between them. Beneath the stripper plates are driven stalk rolls, sometimes referred to as “snapping rolls”, that rotate so as to drag the cornstalks downward through the stripper plate gap which serves to separate the ears of corn from the stalks and husks while slicing up the stalk material. The separated ears are then carried across the top surface of the stripper plates by plural paddles that are affixed to a pair of endless, orbiting gathering chains at predetermined spacings. The chains are synchronously driven by powered drive sprockets. By this means, the ears are carried to an auger that transports the ears to a threshing station where kernels are stripped from the cobs. The cobs, as well as the stalks and husks, are ejected back onto the field.
Even when stripper plate gaps and snapping roller speed are properly set, crop losses can occur that can significantly affect a farmer's bottom line. For example, if inspection of the ground behind the combine shows only two kernels per square foot or only one ear of corn in a row, it potentially represents a loss of one bushel/acre. Thus, on a thousand acre field and with corn priced at $4.00 per bushel, it represents a loss of $4,000.00.
Studies have shown that over one-half of corn harvest losses occur at the cornhead. Shelling of corn kernels due to impact of ears on the stripper plates and conveyor paddles (termed “chatter loss”) also results in loss of yield when those loose kernels are not captured, but are allowed to fall from the stripper plates to the ground.
It is accordingly a principle purpose of the present invention to provide improved row units for combine cornheads that serve to reduce yield losses of the type described above.
In prior art row units, the stripper plates are like those shown in the Calmer U.S. Pat. No. 8,171,708 or the Becker U.S. Pat. No. 6,237,312 where the rectilinear edge portions of the pair of stripper plates defining the stripper gap are inclined downward toward the ground. This allows loose kernels resulting from impact chatter to fall through to the ground. Moreover, no means are provided in the prior art for sweeping loose kernels collecting on the top surface of the stripper plates from the plates into the auger leading to the thresher so as to become part of the yield. Instead, the loose kernels vibrating off the stripper plates onto the field where they are lost.